Magnetic heads for disk files may now be supplied in the form of a complete magnetic head arm assembly in which a pair of sliders carrying the transducing elements are mounted on suspension flexures, which in turn are attached to a common support arm. The head arm assembly is adapted for mounting on the head positioning actuator.
With this type of magnetic head arm assembly it is necessary to connect the fine wires, carrying the head signals, to printed circuitry carried by the moving portion of the head positioning actuator.
Connection of the leads from a large number of heads to such printed circuitry is very labour intensive as each individual head lead must be placed over and soldered to a corresponding conductor or terminal pad. Also, because of its intricacy, this process can give rise to a low yield.
An article by J. P. G. Duman et al. (IBM Technical Disclosure Bulletin Vol 20 No. 5 Oct. 1977, p1984) entitled "Actuator Assembly for a Disk File", shows such connections for a rotary actuator having a rigid arm with compliant head suspensions mounted on the arm in which the signal processing electronics are mounted on a rigid printed circuit board (PCB) mounted statically alongside the actuator. Connection to the PCB is via a flexible tape cable having one end connected both electrically and mechanically to the PCB end and the other mounted on the arm, with a free portion of flexible cable in between to facilitate actuator movement. Connection of the head leads to the flexible cable at the arm end is achieved by soldering of the free ends of the leads to exposed contact pads on the end cf the flexible cable mounted on the arm.
A further example of head lead connection to a circuit is given in an article by J. T. Young (IBM Technical Disclosure Bulletin Vol 20 No 12 May 1978 p5350), entitled "Tape Cable Clip". This shows another arrangement with head leads connected to conductors in a tape cable. It includes a clip, whose primary function is to retain the tape cable to the arm. As a secondary function, the clip also retains the free ends of the head leads against the arm and provides strain relief for them. It achieves this secondary function through a sprung member with channels which cover and clamp the head leads to the arm at a point some distance from the point of connection to the tape cable. No details are given of the method of attaching the head leads to the cable but, in the IBM 3310 Disk Storage Facility, which employs the described arrangement, the free ends of the head leads are manually bent and positioned to lie over contact pads on the tape cable, whereupon solder is applied to bond the lead ends to the tape cable. Thus the clip provides limited retention of the leads to assist manual soldering but does not avoid the manipulation of individual leads.
In an article entitled "Magnetic Wire Preparation for Automatic Wire Bond" by A. Ilgovsky and A. A. Mirza (IBM Technical Disclosure Bulletin Vol 26 No 11 Apr. 1984, p5989), a head arm assembly is shown in which the ends of the head leads are not left free but are soldered to a small terminal board. Although this board facilitates connection of the head arm assembly to the external circuitry in that it is sturdier and more stable than the free head leads, it does introduce an additional connector and multiplies the number of electrical termination operations needed, with a consequently greater chance of failure of the component.
It is well known to connect integrated circuit chips to external circuitry by means of so called "lead frames". These are patterns of metal fingers which locate on respective pins of the chip. A lead frame which is itself encapsulated in a plastic material support shell is shown in an article by W. R. DeBoskey entitled "Directly attached integrated circuit lead frame" (IBM Technical Disclosure Bulletin Vol 15 No 1 Jun. 1972, p3O7).
An article by K. R. Dust (IBM Technical Disclosure Bulletin Vol 24 No 9 Feb. 1982 p4473) describes methods for connecting a pattern of conductors on a flexible circuit carrier to a similar pattern of conductors on a rigid carrier. The article mentions as background the possibility of stripping away a region of the flexible material to leave a window across which only the conductors extend. These conductors would then be soldered onto the rigid carrier. This method of stripping away flexible material is ruled out because it would be prohibitively expensive, and the article goes on to describe mechanical means for connecting the two patterns of conductors. Neither technique is applied to magnetic head lead termination. In the case of head leads, neither method would provide a solution to the problem of terminating the individual head leads.
Pending European Patent Application No. 88303926.5 proposes one solution to the problem of head lead termination, namely that all of the leads from an individual magnetic head arm assembly (typically six leads) should be terminated on a head lead locating frame, across which the leads are guided and maintained in a fixed spaced apart relationship. The head leads are thus prepositioned by the frame for registration with and electrical connection to a correspondingly spaced conductor pattern on a printed circuit connector mounted on the actuator mechanism. Once a particular frame has been aligned with the appropriate conductor pattern, all of the head leads within that frame can be soldered as a group by, for example, wave or probe soldering, without the need to manipulate individual leads. However, in a disk file with a large number of heads, several of such frames must be used, each one requiring an alignment and soldering operation.
Therefore apart from this copending application, which is not publicly available, the prior art does not provide a magnetic head/support assembly in which the head leads can readily be directly connected to external circuitry in an automated or semi-automated fashion.